1. Dermis and Hypodermis

2. Dermis zLies deep (beneath the epidermis) zProvides strength and elasticity to the skin zCreates framework to support the accessory structures zMade of 2 layers

3. Papillary Layer zMade of areolar tissue zContains capillaries and sensory neurons that serve the epidermis above zThe top of this layer has dermal papillae that connect to the dermal ridges of the stratum germinativum

4. Reticular Layer zMade of a mesh of dense irregular connective tissue w/ lots of collagen and elastin protein fibers zContains hair follicles, sweat glands, oil glands, blood vessels and nerves zThe collagen and elastic fibers allow the skin to stretch and change shape

5. Skin Damage zAging, hormones, and UV radiation can all damage and reduce the amount of elasticity of the skin causing wrinkles and sagging

6. Hypodermis/Subcutaneous zFibers of the reticular layer extend into the subcutaneous layer so there isn’t a distinct line between the two zMade of areolar and adipose tissue zStabilizes skin while allowing movement zAreas of subcutaneous fat change during a person’s life zLocation of injections

7. Accessory Structures/ Hair follicles and hair zHuman body has appox. 5 million hairs and 98% of them are on the general body not on the head zHair bulb- bottom of hair surrounded by epithelial cells zHair shaft- the part of hair we see zHair color- determined by the amount of pigment

8. Function of Hair zProtect scalp from UV radiation, insulate the skull zPrevent entry of foreign particles zSensitivity (nerves at base of each hair) zInsulation (erector pili muscles in the skin cause hair to stand on end)

10. Glands in the Skin zSebaceous Glands- secrete sebum, which prevents bacterial growth, lubricates and protects hair and skin, ex. of a Holocrine gland yBlocked sebaceous glands cause acne zSweat glands- 2-5 million sweat glands, cools body temperature yMerocrine- palms, soles, secrete onto surface of skin yApocrine- in armpits, groin, secrete their products into a hair follicle

13. Injury and Repair zStep 1- bleeding triggers inflammation zStep 2- Scab forms, phagocytic cells remove debris, cells from the stratum germanativum migrate to the area zStep 3- Fibroblasts create a meshwork to connect tissue zStep 4- Fibroblast continue creating scar tissue